Abstract: When detecting low-attitude windshear with airborne weather radar, the real signals are usually covered with strong clutter. In this paper, a novel method of low-attitude windshear speed estimation based on Space-Time Adaptive Processing (STAP) is proposed to solve the above problem. The proposed method handles the range-dependence of clutter of airborne forward looking array with space-time interpretation theory to achieve the Independent and Identically Distributed (IID) samples used in the clutter covariance matrix estimation; then the space-time adaptive processor is constructed which is applicable to a distributed low-attitude windshear target to suppress clutter and accumulate windshear signal; finally the accurate estimation of wind speed is got. The experimental results show that the proposed method can achieve a superior clutter suppression performance and an accurate wind speed estimation in high clutter-to-noise ratio and low signal-to-noise ratio.